<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css ">
.nav1{
width:100%;
height:64px;
background:(0,0,0);
position:absolute;
}
.nav{
width:100%;
height:64px;
background:(255,1,0,1.5);
position:absolute;
}
</style>
</head>
<div class="nav1">

</div>
<div class="nav">

</div>
</body>
</html>